Process of roasting ores.



QPATENTED' APR. 18, 1905 S. B. PATTERSON.

PROCESS OF ROASTING ORES.

APPLICATION IILED 3111.21. 1902'.

UNITED STATES Patented April 18, 1905.

PATENT OFFICE.

PROCESS OF ROASTING ORES. A

SPECIFICATION forming part of Letters Patent BIO/787,540, dated April 18, 1905. Application filed January 21, 1902. Serial No. 90,692-

To all whom it may concern.-

Be it known that I, SEELY B. PATTERSON, a citizen of the United States, residing at Phillipsburg, in the county of Warren and State of New Jersey, have invented certain new and useful Improvements in Roasting Ores, of which the following is a specification.

The object of the present invention is to provide an improved method of roasting ores, especially iron ores for the removal of sulfur, which shall render them more easily reducible in the blast-furnace and in which neither sulfur nor ash is mixed with the ore and in which a substantially uniform temperature is maintained throughout the mass, whereby cintering is obviated.

To these and other endshereinafter set forth the invention, stated in general terms, comprises intermittently feeding charges of ore, intermittently subjecting them throughout their length to the action of hot air, and in the intervals subjecting the lower portions of the charge that have been subjected to the hot air to the action of steam; and the invention further comprises the improvements hereinafter described and claimed.

Referring to the accompanying drawings, I have illustrated a type of apparatus capable of use in the practice of the process.

In the drawings, Figure l is a central sectional view, and Fig. 2 is a sectional view taken on the line '2 2 of Fig. 1.

For the sake of a further description the process will be described as practiced in connection with the apparatus shown in the drawings; but other types of apparatus may obviously be employed. Air heated to the necessary temperature to most efliciently desulfurize'the particular ore under treatment is forced through connections 1 at or near the bottom of the kiln 2 and passes up and out through the top thereof, which is fitted with a door or cover 3, that canbe opened or removed, so as to permit the air to pass out. After an interval of, for example, an hour air is turned ofi at the connectionsl, and superheated steam of, for example, 600 to 800 Fahrenheit is. turned in and enters the kiln 2 at or near the bottom and, for example, at the steam connection 4. The steam does not pass entirely escapes at 3.

, shaft.

through the kiln, and exit-pipes 5 are provided and extend from the sides, for example, ten or twelve feet above where the steam enters. Of course the distance depends upon the size of the apparatus. These exits 5 are closed when the heated air is being forced through the material in the kiln, but are open when the steam is being used, and the cover 3 is also closed when the steam is being used, so that when the air is used the exits 5 are closed and the cover 3 open, and when steam is being used the exits 5 are open and the cover 3 is closed.

The operation may be described in connection with the apparatus shown in the drawings, as follows: The kiln 2 is filled with ore, the door 3 at the top is open, the connections A and 5 are closed, and the heated air entering, as at 1, passes up through the ore and After this operation has been continued for a sufiicient time the temperature at the bottom of the kiln is substantially that of the entering hot air. The shaft or kiln may be made sufficiently high to permit the air to impart substantially all of its acquired heat to the ore, so that the air passes out at the top at a little, if any, above the temperature of the atmosphere. It might be said for the sake of description that the described operation is continued for an hour. Thereupon the hot air is shut ofi, the door 3 at the top closed, the valves in the exits 5 opened, and superheated steam turned on at p the connection 4, for example, for four or five minutes. The steam passes up through the lower portions of the charges that have been subjected to the hot air. The steam is then turned off, the valves of the exit pipes 5 closed, and the top doors 3 opened preparatory to again passing hot air through the However, before the hot air is again passed through the shaft some of the roasted ore is removed from the base of the furnace for example, by running it into the furnacebuggies by opening the gates at 6. For the sake of description it may be assumed that this removal of ore lowers the mass in the wide part or base of the kiln two and onehalf feet and that the height from the bottom to the lower ends of the exit-pipes is ten feet, so that every portion of roasted ore removed has been subjected four times to the action of superheated steam.

In connection with the treatment of iron ore by means of the described process the free oxygen of the hot air oxidizes the sulfur of the ore to sulfurous acid (S02) and the iron to sesquioxid, (FQ2O3,) for example, thus:

and the sulfurous acid passes out at the top of the kiln. The oxygen of the steam oxidizes the iron to sesquioxid, (Fe2O3,) and the hydrogen converts the sulfur into sulfureted hydrogen, (F125,) for example:

The sulfureted hydrogen of course escapes from the kiln by way of the exits 5. It is obvious that the heated air takes off a part of the sulfur and oxidizes a part of the ore and that the steam takes off additional sulfur and oxidizes additional parts of the ore. Thus the sulfur,-or substantially all of it, is removed from the oref The air could be taken out of the kiln by way of the exits 5 and the steam by way of the top; but as a matter of economy the heat of the air is more completely transferred to the ore by permitting the air to traverse the length of the stack. Moreover, the loss by taking the steam out quickly is small, as the temperature of the steam need not be as high as that of the air, and the application of steam is of short duration.

Among the many advantages of the method constituting the present invention the following may be mentioned: In the use of solid fuel, which usually contains sulfur, sulfur is added to the ore and ash is mixed with it, whereas in the present method these disadvantages are obviated. In burning solid fuel or fuel-gas in the midst of the ore it is difficult to maintain a uniform temperature throughout the mass and to properly regulate and prevent it from getting too high, (and yet keep it high enough,)so that the ore is liable to be cintered or melted, whereby the reduction in the blast-furnace is difficult, since the free silica tends to form silicates. In the described process the current of hot air can be caused to keep any desired temperature, and the temperature is uniform throughout the mass. In roasting ore with producer-gas the free oxygen is much more diluted than when using air in accordance with this in vention,because in burning the gas takes up oxygen in the conversion of carbon monoxid to carbon dioxid. In the process of this invention the reagents--air and steam-will thoroughly permeate the mass, because they are forced through it.

It will be obvious to those skilled in the art to which my invention appertains that modifications may be made in detail without departing from the spirit thereof: Hence I do not limit myself to the precise construction and arrangement of parts hereinabove set forth, and illustrated in the accompanying drawings, nor to the exact mode of procedure above explained; but,

Having thus described the'nature and objects of my invention, What I claim as new, and desire to secure by Letters Patent, is

1. The process which consists in establishing and continuously roasting a body of ore, intermittently feeding charges to the top of the body, intermittently subjecting the body throughout its length to the action of hot air, in the intervals repeatedly subjecting the lower portions of the body that have been subjected to the hot air to the action of steam, and withdrawing the roasted ores from the base of the body, substantially as described.

2. The process of roasting ore which consists in establishing a body of ore, intermittently feeding and withdrawing charges, and subjecting the body of ore alternately and in layers to the action of hot air and steam at lower temperature than the air, substantially as described.

In testimony whereof I have hereunto signed my name.

- SEELY B. PATTERSON. Witnesses Gr. Gr. STRYKER, JAooB NASE. 

